Fermentative preparation of L-leucine

Abstract

L-leucine is prepared by cultivation of an analogue-resistant mutant of Brevibacterium thiogenitalis in an aqueous nutrient medium under aerobic conditions. The cultivation is preferably carried out at about 30° C. and at a pH of 5 to 8. L-leucine is recovered from the fermentation broth.

What is claimed is: 
     
       1. A process for preparing L-leucine which comprises cultivating under aerobic conditions a mutant strain of Brevibacterium thiogenitalis resistant to an analogue of L-leucine selected from the group consisting of α-amino-β-hydroxyvaleric acid; methallylglycine; and β-hydroxyleucine, to yield a fermentation broth, accumulating from about 0.1 to about 6 grams/liter L-leucine in said fermentation broth, and recovering the accumulated L-leucine from said fermentation broth. 
     
     
       2. A process as in claim 1 wherein the mutant is Brevibacterium thiogenitalis ATCC 39104. 
     
     
       3. A process as in claim 1 wherein the fermentation is carried out at a temperature of from 20° to 45° C. for from 16 to 176 hours. 
     
     
       4. A process as in claim 1 wherein the pH of the fermentation media during cultivation is from 5 to 8. 
     
     
       5. A process as in claim 1 wherein the mutant is Brevibacterium thiogenitalis ATCC 39104 and fermentation is carried out at from 25° to 40° C. for 16 to 176 hours at a pH of from 5 to 9. 
     
     
       6. A process as in claim 1 wherein the analogue is α-amino-β-hydroxy valeric acid.